The IRIS™ imaging catheter developed by Voyage Medical is capable of direct visualization of endocardial tissue during minimally invasive Electrophysiology procedures for the diagnosis and treatment of cardiac arrhythmia diseases. The imaging catheter is also capable of delivering Radio Frequency energy to cardiac tissue via the use of electrodes and saline irrigation, where the saline serves to both displace blood for direct optimal imaging and as a conductive medium for RF energy delivery. With data available from the imaging and electrical recording apparatus, the invention discloses a variety of methods to monitor and measure energy delivery to cardiac tissue and the progress of RF ablation therapy. Methods are also disclosed that aid with the titration of the energy delivery process and optimization of treatment efficacy.
Current methods of monitoring RF energy delivery during cardiac ablation consist mainly of reviewing parameters on the RF generator used in the process, such as Wattage delivered as a function of time and total energy output from the generator. However, these are only coarse measures, as a (generally unknown) portion of the energy output is actually delivered to blood rather than to endocardial tissue. Furthermore, there are currently no commercial direct imaging catheters available and the post-therapy state of the tissue is an unknown.
The methods of the present invention are intended to be used in conjunction with the IRIS™ imaging catheter to generate a variety of measures of efficacy of energy delivery.
In addition to power delivered as a function of time, local tissue impedance is also available with current RF generators used in RF ablation energy delivery in Electrophysiology procedures. However, typical ablation catheters have a single tip electrode, and the impedance measured is associated with the contact of the single tip electrode with cardiac tissue. This is a coarse measure and no further granularity is available.
In summary, currently available methods in the art for monitoring and measurement of the progress of RF therapy delivery are very limited in scope. There is a significant need for more improved measures of RF dosing and to monitor the intraoperative progress of RF therapy.
The present invention discloses methods to address this need for better monitoring of therapy delivery in RF ablation procedures.